The use of RFID tags are quickly gaining popularity for use in the monitoring and tracking of an item. RFID technology allows a user to remotely store and retrieve data in connection with an item utilizing a small, unobtrusive tag. As an RFID tag operates in the radio frequency (RF) portion of the electromagnetic spectrum, an electromagnetic or electrostatic coupling can occur between an RFID tag affixed to an item and an RFID tag reader. This coupling is advantageous, as it precludes the need for a direct contact or line of sight connection between the tag and the reader.
Addition of supplemental power to RFID tags, e.g., from a battery, has greatly increased the range in which reliable communication with the tag is possible. This has in turn made new applications possible.
One concern with self-powered electronic devices is the life of the battery. Battery-powered devices draw very little power when inactive or turned off, but draw orders of magnitude more power when active. If the electronic device has been activated many times, the battery will be used up more quickly than for a device activated less. Because certain electronic devices are active more often than others, depending upon the duty cycle of use and/or may simply draw more power than other devices, it is hard to estimate the battery life of a given electronic device. In a situation where there are many electronic devices, the current method is to replace all batteries when the battery on one of the electronic devices dies, as it is likely others will die soon as well. However, it is quite possible that many of the batteries may still have a reasonable useful operating life remaining. Thus it would be desirable to provide an indication of the condition of a battery of an individual electronic device.